1. Field of Invention
This invention relates to agricultural machines having crop harvesting headers, and more particularly to agricultural machines having a mode of operation that automatically adjusts the pitch angle of the header during manipulation of the header height.
2. Description of Related Art
Harvesting machines are commonly used to sever standing crops in the field and deposit the crop back onto the ground in the form of a windrow or swath to sever. A header at the front of the windrower cuts the ripened crop from the field. The crop is transported to the rear of the header and forming shields form a windrow of the crop between the tires of the machine for natural dry down of the crop. A subsequent field operation picks up the windrows for further processing, such as separating and cleaning in the case of grain crops, or baling or chopping in the case of hay.
Platform headers and draper headers are header types commonly used when harvesting crops such as small grains, peas, lentils, and rice. For example, U.S. Pat. No. 6,158,201 to Pruitt et al. entitled “Rotary Mower Conditioner Having Improved Crop Flow” discloses an exemplary header. When operating the header, it is desirable to have the ability to adjust the height at which the crops are cut off and also to sense and change the vertical position of the header to follow changing terrain. To accomplish this, it is known to use a header float system or a terrain following system to enable the header to follow the ground over changing terrain without gouging or digging into the soil. It would also be desirable to adjust the fore/aft pitch of the header to select the angle of the cutter bar to optimize crop cutting and feeding into the windrower. Based on the foregoing, it would be desirable to have a header control system that accommodates both cutting height and tilt on the header.